When Stewart Fraser saw it, 40 miles off the North Island's Karikari Peninsula, he wasn't sure he even wanted on his boat, he told the UK's Mail Online.
"I was in two minds whether to haul it in, but curiosity got the better of me and I decided to take a closer look," he told the Mail. "It was quite something, and I'd never seen anything like it before."
Dennis Gordon, a scientist with New Zealand's NIWA water and atmospheric research agency, told the New Zealand Herald the see-through creature is a salp, and it's really not that rare. Salps are found around the world, and often in big numbers, scientists say. While Fraser pulled up a lone salp, scientists say they have often been found in chains more than 30 feet long.
And Gordon said some salps reproduce so rapidly that they can double their population in a day.
But obviously, they are really hard to spot, which protects the salp from other creatures that would like to make a meal of them, Paul Cox, director of conservation and communication at the National Marine Aquarium, told the Mail.
"In common with other defenseless animals that occupy open water -- jellies and hydroids for example -- the translucence presumably provides some protection from predation. Being see-through is a pretty good camouflage in water," Cox said.
Gordon told the Herald that when they can be caught, scalps are a good food source for some fish, seals and turtles. They are more nutritious than jellyfish, he said.
He also said the salps, which feed by taking in water through internal filters, are important predators themselves, but not one that any human needs to be afraid of.
"They can eat the smallest plant plankton and can even eat bacteria, so they can exist in parts of the ocean where nothing else can live. The significance of that is they are an intermediary in the food chain,'' the Herald quoted Gordon as saying.
So what does a rapidly reproducing, filter-feeding, translucent predator feel like?
"Scaly and was quite firm, almost jelly like," Fraser told the Mail.